A suggestion that may be helpful: Put some green heat shrink on the scopes earth ground leads - it will constantly remind you it is an earth conductor and not just another test lead as in the case with multi-meters

Thank you so much! There are very few sources of information so clear and so well explained as your video. So many people adopts measures that risk security, as it is the case of neutralizing the grounding of the oscilloscope to make measurements.

Thank you for a comprehensive video on this subject. I have seen EEVblog' s video on this subject, but he doesn't show the use a RCD/GFCI gadget, at least not on any video I have seen of his. I have seen dozens of videos on scopes, but they never showed the use of a GFCI in USA, RCD in Aus and Europe. I personally have 22 circuits and all of these have RCD's on them. They are compulsory in all new homes in Australia,,, and one cannot sell / transfer an old house without having this gadget installed.

Thank you. This is EXACTLY the info I’ve been looking for!

Wish I watched this before I burned up my power supply 😢 Thanks for the education!!

Excellent lecture!

IT'S REALLY REALLY GOOD!!

It would be most helpful if you could show what you can do about this. In the olden days, one used isolation transformers, differential input Scopes made for line voltage use etc. Today many cheap scopes have low voltage psu, such as USB power via powerpack.

Thank you. "Oscilloscopes are not multimeters!" is the perfect way to phrase this message. Although I have never conflated the two tools, thinking of it this context will prevent me from making dumb errors in judgement.

Early cardiac monitors are connected to an oscilloscope (to display the ECG waveform).

Always check power line (outisde or inside devices) before contacting a oscilloscopes probe tip connectors: Always be sure where is the hot phase line where is ground line of power AC outlets / cables line also inside any opened device to be repaired. Better measure again if unsure about it or forgotten, before risking to make any bad contact.

This is a very good video. Do you know much about ECMO machines? If you have an idea, a video on how they work would be good, or at least the oxygenator, how the membrane exchanges the CO2 and the O2 and the pump.

7:31 In household electric systems the direct connection between the neutral and ground is only done once in the first breaker panel and must not be done again in additional sub panels. If a sub panel is being added to a home it may already have a bonding screw between neutral and ground and this bonding screw must be removed for sub panel usage of a breaker panel. Just a little detail from renovations that occasionally gets missed.

i know this is a older video, but everybody on KZfaq who makes video's about Oscilloscope Safety and measuring mains voltage, left one part out of the video. If you simple want to see the 50 or 60Hz sine wave of your mains outlet, you don't need to connect the ground lead of your scope probe. Your mains is ground referenced, but also the tip of your scope probe is ground referenced, so you don't need to connect the ground lead, and for extra safety, you can best removed your ground lead from your probe, that way this lead can't accidently touch something. Simple set your scope probe at X10 setting, and only use the tip of the probe and you can touch Hot / Line / Phase / Neutral without risk. If you want to do measurings in a circuit or device that is powered from mains, and you want measure across components in circuit, or circuits that use higher frequency then 50 or 60Hz, you will get more noise when the ground lead of the probe is not used, and this method of only using the probe tip cannot be used.

Hi @Engineering Technology for Healthcare, I have just found this video and your channel, you have condensed the information nicely (I have subscribed). Could please inform us of what BMET is / stands for, I have searched the web but can only find references to Bermingham University or a blood test? Thank you and have a good day.

THANK YOU!

Thank you sir.

My oscilloscope is on a circuit protected by a combination GFCI and AFCI (arc fault) circuit breaker. It tripped immediately when I accidently connected the ground probe to a hot voltage source. That saved everything!

Excellent info! How would I safely use a oscilloscope to see the pure sine wave of a 12v Inverter that has a earth ground? Thanks!

Is it safe to say never apply power to the ground lead? Would this cover all situations? And if you were worried could you just wire in an inline glass fuse?

It would be nice to explain if the situation changes with battery operated oscilloscopes.

Thanks!

Cheers for that Dude! If the scope is USB powered by a 2 pin 5v charger - does that do away with the mains issue - leaving only the potential difference possibility?

Even if you did do that -- it would just flip the breaker in the house panel. But I get your point: be cautious where you put the ground leads.

Great video thanks. But as a total vovice where is it safe to connect a scope? Will it damage a scope on say 30volts? My scope says max input voltage of 300v? Rohde & Schwarz RTB 2002 (Not that I would ever use that voltage) Any chance you could expand a bit and do a video where it is safe to connect on a cicuit board? (obviouslly not the mains input)

This material is based upon work supported by the National Science Foundation under grant number 1700649. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect those of the National Science Foundation.

Thank you so much ( I'm 3 years too late ), but if you still active do you have any suggestions for what hardware I could start learning the oscilloscope? I was thinking USB power bricks or just order bunch of components from web and go to town. I'm hands on learner that's why I am asking.

0:56 "The multimeter probes have a high resistance between each other" -- This is *only* true if the meter is set to voltmeter mode. *The ammeter mode will short the leads to each other!*

Manufacturers are now making oscilloscope with dmm and waveform generator modes

So just to clarify, you are saying to plug the oscilloscope into the gfci outlet?

Quick question - if you were using a battery powered oscilloscope, wouldn't that isolate the o-scope from the ground? I know there are several models that may not be as accurate or as full featured, but which are adequate for purposes of say, diagnosing audio equipment issues?

As a novice in oscilloscopes I isolate myself from this issue by having a cheap USB scope that is connected to my laptop that runs on batteries. Also I make sure other parts of the laptop are not connected to the circuit I'm disturbing with the probe (something like arduino board connected to the same laptop via USB and I'm probing something that's connected to that board).

I have a question: you can only check for continuity between neutral/neutral and ground/ground out but not live wire/live wire to live wire right?. I was under the impresion that you would destroy your multimeter if you try to measure continuity while power on dc or ac.

Thank you for the info. However, you advised the novice as to what was unsafe to do but not what was proper and safe. Of the neutral, ground and hot wires -- you said to not connect probe ground to the hot. That still leaves the neutral and the ground to choose from. Can a newbie assume either is OK? (I think assumptions are never safe!) Also will you please detail the steps to determine if it is safe to connect ground to a point in a circuit when one is not sure if it is connected to hot, neutral, or ground? Thanks again for sharing your knowledge.

my osci isnt connected to ground, only 220V AC. would that still be a problem probing voltages with the ground pin?

What about hand held, battery driven scopes? They are not grounded, or are they?

If you are addressing this to hobbyists you should have mentioned the use of isolation transformers. That is how you avoid damaging your scope. The transformer isolates the circuit under test from the power supply ground.

Why isnt there a fast blow low current fuse in that ground?

So the battery operated scopes will be fine?

USB power from a battery or 2 prong wall transformer should be okay since it is floating?

Ok little lost I have a fluke 199 and it’s has no ground on the plug and normally I run it off it’s battery so now you got me wondering what would happen 🤔

Could you not run a safety neon in probes that will take the current in this event.

So Now How I probe the high voltage circuit with oscilloscope

Well , very simple . Use an isolated battery pack supply for your oscilloscope, just like the DMM . As long as the DC ground is totally separated from the earth/neutral AC , you should be golden !!!!

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Never do u hook the ground side of the ociliscope to hot ac. Wtf

Technically it's called a Napolean connection. You heard of Napolean Blown Apart, haven't you?

Umm. Mine is.

If I buy battery operated oscilloscope then there will be no problem ,I can use oscilloscope like multimeter

Sorry mate you got that very wrong about multimeters (battery or bench). If you set your meter to measure current (usually involves moving the probe to the current socket on the meter) then if you then want to later on measure voltage - and forget to change your probe socket, you then can short out whatever volts measure which may destroy your meter. This is easily done, ask any tech who is honest enough to admit it.

Use a cheater plug to float the scope.

That is why my Rigol is powered via separation transformer😂

YOUR INCOMPLETE EXPLANATION IS IRRESPONSIBLE AT BEST. "PORT" ??? THEY ARE CALLED CHANNELS SIR. CHANNELS.